RE: Irvine 72 tach readings
Sorry it has taken a few days to get the data.
Irvine 72
Looks like it has a stock muffler with exhaust extension.
Prop: 13 x 8 MA classic
RPM: 9200/9300 RPM
Thrust: 8# 9oz
Fuel: 20% nitro
The engine is on a 4* 60, which does not have a cowl. No attempt was made to retune for maximum RPM since the airframe drag is big and airspeed changes little from half to full throttle. The thrust varied between 8# 6oz to 8# 13oz and settled in at 8# 9oz.
Notes from a year ago indicate:
Prop: 14 x 8 MA
RPM: 8100/8200 RPM
Notes indicate the prop was changed because the engine sounds better with a 13 x 8. Both props had lots of Hi needle range.
Hope the information helps.
Bill